So hold on, Even if i didn't wanna be Teacher, But wanted to make video games in japan, the immigation office wouldn't allow me to work there?
Reread what I wrote. My statement referred to PE teaching or dietician. Your current degree might very well be accepted for visa purposes for a programming job, yes, but not for those other two.
That still doesn't mean you'd get hired as a programmer, though. And, job comes before visa. Lots of people outside Japan want to "make video games", but what can you do that a Japanese can't? That's the key to getting hired here, plus the ability to read/speak/write Japanese fairly well (in non-English teaching jobs, anyway).
I forgot to mention that i would like to be a teacher i wanna go for a teacher degree at some local college.
Local meaning where you are, or in Japan? In Japan it will mean knowing a heckuva lot of Japanese! If you mean where you live, the degree/license does not give you much of an advantage here. To work in an international school, you'd also need 2 years of experience in your homeland. To work in any public school in Japan, the degree/license back home doesn't help you get in; you'd still have to go through Japanese uni or get on as a mere ALT. As for other types of teaching work here (conversation school, uni, business English agency, etc.), a teaching degree is nice but not required by employers. If you are really interested in getting your feet in the door of a Japanese school, I'd recommend applying for the JET Programme (only once a year). They put people as ALTs in several public schools assisting a real licensed Japanese teacher. Experiences vary. Ask the posters on Bigdaikon.com.
Correct me if i'm wrong here, But after a certain amount of time being a ESL teacher don't i get a certificate or something
Nope, no such thing. What did you hear? I've been in the teaching biz (conversation school, HS, uni) for almost 15 years in Japan, so I think I have a pretty good handle on that profession.
Certificates are training-issued parchments, like those from CELTA or Trinity, which are programs you pay to attend. You don't earn them by mere longevity in teaching. You get nothing additional just for sticking it out as a teacher. No license, certificate, medal of honor, etc.